This invention relates generally to control units for controlling the operation of associated power driven devices such as medical and dental equipment, power tools, recording equipment, office machines, and motor driven appliances. More particularly, the present invention relates to foot operated control units wherein the control unit is actuated by the foot of the operator to energize, de-energize, or similarly control the operation of an associated power driven device.
Most conventional foot operated control units are connected to the controlled device by a cord or cable that carries the command signal from the control unit to the controlled device or completes the power supply circuit between the control unit and the controlled device. In many applications, the use of a hard-wired connection between the control unit and the controlled device can be inconvenient. For example, the cable and its connectors have a limited number of conductors and pins. This limits the number of control options that can be controlled through the hard-wired connection. In addition, it is generally difficult to change the control functions without cable and/or connector modification. Personnel may trip on an exposed cable. The conductors and/or insulation of exposed cables may be damaged if walked upon. Heavily armored cord sets are unacceptably stiff and bulky for many applications. Cable clutter is unaesthetic and makes “house cleaning” more difficult.
Wireless, radio frequency (RF) control units have become quite common. Perhaps the best known are the RF control units used in wireless local area networks. RF foot operated control units are also known and solve many of the problems found in hard-wired systems. However, the RF signals used by the control units can interfere with the operation of other equipment that is located within the range of the control unit. Conversely, other sources of RF energy may interfere with signal from the RF control unit. Accordingly, RF control units are not appropriate for controlling certain types of controlled equipment, for example medical equipment.
Wireless control units utilizing light wavelengths that are invisible to the human eye, for example infrared (IR) light or ultraviolet (UV) light have also become quite common. For example, IR remote controls have become ubiquitous in the consumer electronics market. Such control units operate on either a line-of-sight (LOS) or non-line-of-sight (NLOS) approach. With a LOS approach, an unobstructed path between the transmitting and receiving points is necessary. LOS is also limited by off-LOS alignment of the transmitter and receiver. However LOS is a simple engineering design, having one transmitter and one receiver, and is the type of approach used by most of the commonly found light control units. With a NLOS approach, obstructions of the media and the alignment issue are virtually eliminated. However, an NLOS approach requires greater sophistication in the design of the transmitter and receiver.